How to Make It

Step 1

Preheat the oven to 425° and line a large, rimmed baking sheet with parchment paper. In a large bowl, toss the potatoes, parsnips, celery root, beets and garlic cloves with 3 tablespoons of the oil and season with salt. Spread the vegetables on the baking sheet and roast on the bottom rack of the oven for about 1 hour, stirring occasionally, until browned and very tender. Let cool slightly.

Step 2

Meanwhile, in a medium ovenproof skillet, heat the remaining 1 tablespoon of olive oil until shimmering. Season the roast with salt. Add it to the skillet and cook over moderately high heat, turning, until browned all over, about 5 minutes. Transfer the roast to a plate and pour off the fat in the skillet. Add 2 tablespoons of water to the skillet and cook, scraping up the browned bits on the bottom of the pan. Pour the pan juices into the large bowl.

Step 3

Return the meat to the skillet and roast in the oven for 25 minutes, until an instant-read thermometer inserted in the thickest part registers 115° for medium-rare meat. Transfer the roast to a board; season with black pepper.

Step 4

Squeeze the roasted garlic cloves from their skins into the meat juices in the bowl and mash with a fork. Whisk in the vinegar, peppercorns, brine and honey. Add the roasted vegetables to the bowl and toss with the dressing. Add the arugula and toss again.

Step 5

Carve the roast into thin slices and serve warm or at room temperature with the salad.